Vertices not working?
You should check if those vertices are duplicates. It looks like vertices being overlapping (2 or more in the same space). It happens a lot when trying to extrude, then "forgetting" to move your extrusion

Correct this issue in EDIT mode. Select all by hitting A, then by go to MESH menu, then choose Clean up, merge by distance. If not, there must be something you are doing wrong when extruding, but I am almost sure those are vertices overlapping.